Closed-loop control is known for controlling the speed of machine transmission outputs, such as the ground speed of machines, swing speeds of machine components, or other speed-controlled machine elements. Generally, closed-loop speed control operates by minimizing a difference between a desired speed and an actual speed of the machine element in question. Often, the actual speed of the controlled entity is fed back into a controller, which may implement a proportional-integral-derivative (PID) control scheme, to generate a power command signal. When applied, the power command signal may reduce the difference between the actual speed and the desired speed.
The controller typically generates the power command signal based on various gain parameters. While higher gains initially result in a more rapid response to speed change inputs, these gains may result in instability, such as continuous overshooting or ringing. For more stable speed control, a system may benefit from lower gain values. However, the resultant system may become less responsive to operator control inputs, which can lead to operator impatience and dissatisfaction, and in some cases, may also result in operator errors and inefficiencies.
U.S. Patent Application Publication No. 2014/0316664 (the '664 publication), entitled “Aggressive and Stable Speed Control,” purports to address the problems of stability in control systems. The system described in the '664 publication includes a PID control module configured to periodically change the proportional, derivative, and integral gain values based on a speed error value. However, the system described in the '664 publication may not be well suited to speed control for some types of machines or some machine operating conditions. Accordingly, there is a need for improved ground speed control systems and methods to address the aforementioned problems and/or other problems known in the art.
It will be appreciated that this background description has been created to aid the reader, and is not to be taken as a concession that any of the indicated problems were themselves known in the art.